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View Full Version : replacing the exhaust/intake gasket 2f


bigcity25
11-23-2012, 01:32 PM
My 2f has developed a exhaust leak somewhere at the manifold. When the truck is in gear and engine under load there is a definite noise. I don't have any loss of power (just mpg's) but a strong smell of exhaust in the cab. I can't see any "deposits" of carbon per say but I am pretty sure it needs replacing. The exhaust is almost a year old, desmogged 2f with weber carb and oem intake/exhaust manifold.
My question is: is it pretty cut and dry pulling that apart? Can I keep the carb attached and pull the entire system back as one piece? I ordered a remflex gasket and will start spraying the pb blaster tonight. Any other pearls of wisdom from you guys?
BTW the exhaust tip is behind the rear tire and just sits about 1/4 inch past the body to help avoid exhaust being drawn in.

farnhamstj
11-23-2012, 03:26 PM
Is the manifold oem or do you have an aftermarket header? Difficult part is dealing with rust bolts. Just take it apart and post pics of what you find.

bigcity25
11-23-2012, 04:18 PM
Keepin' it real with the oem exhaust/intake manifold.

rover67
11-23-2012, 06:19 PM
Others may have another opinion, but I couldn't get the remflex gasket to keep from blowing out. Itd seal for a while, but then it blow out where the manifold was warped eventually. It was just too soft and too thick in places I think. I tried it 3 times.

Anywho, I'd say the best thing to do is to try to get the intake and exhaust faced as a bolted together assembly so it is super flat where it hits the head, then make sure all the spots where the washers for the bolts hit on the manifold ears are all the same thickness. So basically where each washer hits make sure when bolted down it pulls evenly on both parts of the manifold. I used a dermal tool and took my time doing it and it worked fine.

Lastly, Use a stock gasket..... and when you torque it, follow the book! It seems like really light torque but it works. Don't be tempted to over tighten or you'll warp the manifolds again and they'll eventually leak.

So anyways, mine (and I've only done one 2f) didn't stay reliably sealed until I did it with the stock gasket, machined flat, and with the washer surfaces all the same thickness. I think others have had good luck with the remflex stuff.

rover67
11-23-2012, 06:30 PM
Oh, and also, it takes a little work to get to the back most bolt... A universal joint on a extension with a short socket should get it. You'll have to work to get it all. It is kind of a job but it goes ok...

bigcity25
11-23-2012, 08:26 PM
Cool thanks for the advice, I was reading on mud that guys liked the remflex. But what threw them a curve was the torque specs. Guess its less lbs for the remflex as compared to the FSM. I rolled the dice with the more expensive gasket. Due to the feedback on mud and remflexs claims. I have no idea if the head is warped so I'll get a straight edge out and check it. I hope that this isn't a real crazy project. But I am sick of smelling like exhaust and I was told exhaust is bad for my......my.....ah......brains.

rover67
11-23-2012, 10:11 PM
I'm not talking about the head being warped, I am talking about the manifolds being warped where they meet the head.

Yes, the folk on mud like the remflex..

bigcity25
11-23-2012, 10:54 PM
Copy thanks

farnhamstj
11-24-2012, 10:04 AM
You will smell exhaust and fuel for as long as you own and drive a fj40. I sold mine 6 years ago and I can still smell it. ;)

bigcity25
11-24-2012, 12:39 PM
You will smell exhaust and fuel for as long as you own and drive a fj40. I sold mine 6 years ago and I can still smell it. ;)

Yeah I got that, but it just got worse and now my clothes stink. So after driving it for the last 2 years there's an obvious change.

Rzeppa
11-24-2012, 02:35 PM
Take the carb off! And x5 on what everyone's said about OEM gaskets for the manifold. What year is your 2F? There are a number of differences. CAREFULLY check the gaskets that go between the insulator and the carb and the intake and exhaust. I *think* the latter is now unobtanium but there may be a few floating around he parts system. I know what Marco wrote about machining the intake and exhaust as a pair flat is widely accepted, but 2 of the 3 bolts that hold the intake to the exhaust go into the aluminum intake and are prone to stripping the aluminum threads.

Don't ask me why I know this...:rolleyes:

bigcity25
11-24-2012, 06:38 PM
I think my 2f is out of a fj60 from the early 80's. That's my best guess. If I can't find those gaskets or my intake gets trashed whats my options. Think this job is not gonna be done by me, might be paying a shop.

rover67
11-24-2012, 07:22 PM
You can do it. If you use the remflex gasket and r&r the manifolds fast and dont split them I'd bet you can do it all in a day on a weekend day. On a week maybe two nights. All the gaskets were available for my 82 fj40's 2f when I did mine.

subzali
11-25-2012, 09:50 AM
Couple thoughts:
1. Take the carb off. It's only 4 nuts and disconnecting some linkage and vacuum hoses.
2. The FSM says to loosely bolt up the manifold assembly to the head and check for any gaps. If there are none you don't need to machine anything. I didn't have to and mine seals fine.
3. Always tighten the bolts up that hold the manifolds to the head first, then tighten the bolts between the manifolds.
3. Also check the hole where the hot air diverter flapper thingy goes through the casting and make sure you're not leaking too much there.
4. Did your desmog eliminate the EGR cooler? Check to make sure your EGR block-off plate isn't leaking if so.
5. Exhaust dump location sounds pretty good, shouldn't be having problems there.

Start reading at this post for a very detailed picture description of how to install the manifolds:
http://forum.ih8mud.com/showpost.php?p=8034231&postcount=152

bigcity25
11-26-2012, 11:38 PM
Couple thoughts:
1. Take the carb off. It's only 4 nuts and disconnecting some linkage and vacuum hoses.
2. The FSM says to loosely bolt up the manifold assembly to the head and check for any gaps. If there are none you don't need to machine anything. I didn't have to and mine seals fine.
3. Always tighten the bolts up that hold the manifolds to the head first, then tighten the bolts between the manifolds.
3. Also check the hole where the hot air diverter flapper thingy goes through the casting and make sure you're not leaking too much there.
4. Did your desmog eliminate the EGR cooler? Check to make sure your EGR block-off plate isn't leaking if so.
5. Exhaust dump location sounds pretty good, shouldn't be having problems there.

Start reading at this post for a very detailed picture description of how to install the manifolds:
http://forum.ih8mud.com/showpost.php?p=8034231&postcount=152

1. Egr cooler, is that the box next to the block with the corrugated tubing? I haven't seen any soot deposits anywhere but I'll check when I get back in town.

subzali
11-27-2012, 09:21 AM
Yes, that is the EGR cooler.

SteveH
11-27-2012, 09:35 AM
Check the other end of the EGR cooler tube where it bolts to the bottom of the manifold. A pretty common leak point, especially on earlier 2F models.

bigcity25
11-27-2012, 10:44 AM
Check, I'll look at it. All this started when I had a backfire. Never had it happen before and it hasn't since. I traced my exhaust from the rear to the front and couldn't find any splits. So that's why I just assumed it may be the gasket, thinking that's the weakest part in the system. And also by the "noise" I get when accelerating.

nakman
11-27-2012, 03:36 PM
You will smell exhaust and fuel for as long as you own and drive a fj40. I sold mine 6 years ago and I can still smell it. ;)

You beat me to it, Farnham.. was going to post almost the exact same thing. :lmao:


great tech thread though, dang! almost wish I had a 2f.. :p:

bigcity25
11-27-2012, 11:06 PM
Check the other end of the EGR cooler tube where it bolts to the bottom of the manifold. A pretty common leak point, especially on earlier 2F models.

Is that needed on my rig? Or should that have been removed for the desmog? I did a little looking and saw some pics how that is plumbed in. Guessing it just "recycles" exhaust for another attempt to burn it up. Hot exhaust goes into the cooler and the fins dissipate heat. Then the "cooler" gas is sucked into the intake when the valve is opened. Does the valve open at certain rpms? Or is it disabled since my engine has been desmogged?

Rzeppa
11-27-2012, 11:29 PM
You beat me to it, Farnham.. was going to post almost the exact same thing. :lmao:


great tech thread though, dang! almost wish I had a 2f.. :p:

I rebuilt the F on my '71, put it back in there and I swear it is even louder than it was before! :eek:

SteveH
11-28-2012, 09:20 AM
The point of EGR is to suck in burned fuel mixture to slow the combustion of the regular air/fuel mix. Slowing the combustion lowers the temps and creates less NOx. Some vehicles can suffer spark knock after disconnecting the EGR, but it's not common on 2Fs, because the compression isn't very high to begin with. You can leave all the equipment in place (for a visual) and plug off the manifold port, if you want. If you have removed the EGR vacuum line, the EGR will not open and exhaust will not flow through that tube.

If I were desmogging, I would put a BB in the EGR line, be sure the EGR valve is actually shut, and cap off that rear manifold port, to prevent current and future leaks. Many people cap it off by dropping a slug of steel in there and welding it in place. You can then bolt the tube right back up and it will look stock/OEM.

bigcity25
11-29-2012, 06:11 PM
Well after looking at my engine bay today the EGR vacuum is capped off. Guess I never used that and tells me I don't need it. So next step is to do some digging,remove and cap that off.